NullPointer Exception

Crash reported at this line:

Line 89 in f22388b

mListener.endSession(mViewModel.getSessionPk());

It seems we've missed lots of cases to detach the listener from the fragment on detach and not even ensuring that activity exists before assigning.

I went through this article. Delegates sounds like a really neat engineering solution for all these cases.

Introduced in commit 69f3e39
Currently, have to update all fragment listeners

Almost fixed.